Several rubbery compositions and their applications have already been described in the prior art.
FR 2.114.383 relates to impact resistant styrene polymers having good flow properties and which can be easily moulded without forming fish eyes.
GB 2.147.906 discloses block copolymer composition comprising at least one thermoplastic elastomeric block copolymer, a polymer of a monoalkenyl aromatic hydrocarbon and a random copolymer. This composition is especialy suitable as shoe upper stiffener.
WO 96/16122 discloses a composition useful for preparing elastomeric articles such as films, fibers, woven and non-woven articles. The composition comprises thermoplastic elastomers blended with other polymers to improve their processing.
U.S. Pat. No. 4,306,034 relates to rubbery compositions and molded polymeric articles therefrom that stimulate the appearance of natural plantation crepe rubber. Those compositions comprise e.g. polarizing agents.
Abstract Derwent of JP 62 256 845 discloses a rubbery composition suitable for structural materials of noise insulating sheets and vibration insulators and for backing materials of carpets.
Abstract Derwent of JP 63 057 663 relates to heat resistant gasket for syringes comprising thermoplastic elastomer consisting of block copolymer, polyphenylene ether resin, paraffinic oil and polyolefin and/or polystyrene.
Abstract Derwent of JP 63 118 359 relates to thermoplastic elastomer composition for shoe sole prepared by adding process oil, inorganic filler and thermoplastic resin to thermoplastic elastomer.
GB 1,196,127 discloses thermoplastic compositions comprising at least 75% by weight of a thermoplastic material. Those compositions are particularly useful for making sealing gaskets for container closures.
The closure of containers, in particular wine bottles, is becoming an important issue because the supply of natural cork is not keeping up with the increased demand for wine bottling in various parts of the world.
Several attempts have been made to replace natural cork with synthetic materials. These attempts are based on formulations that are, among others, adequate to be mixed with a blowing agent. The role of said blowing agent is to allow the creation of cells duplicating the cellular behaviour of natural cork. Among the disadvantages resulting from these attempts one can cite, for example, the lack of uniformity of the foamed resin leading to leakage of the containers, or the need to use additives such as sulfur dioxide as an oxygen scavenger that are detrimental to the quality of the contained liquid.
Particular polymers have been used to bring an improvement. Thus U.S. Pat. No. 5,855,287 describes a synthetic closure comprising hydrogenated styrene butadiene copolymers and at least 1 wt % of a blowing agent. Although this closure achieves its objective it is still unsatisfactory as regards to the relatively high cost of the raw materials used.